Navigation

The opt command is the modular LLVM optimizer and analyzer. It
takes LLVM source files as input, runs the specified optimizations or analyses
on it, and then outputs the optimized file or the analysis results. The
function of opt depends on whether the -analyze option is
given.

When -analyze is specified, opt performs various analyses
of the input source. It will usually print the results on standard output, but
in a few cases, it will print output to standard error or generate a file with
the analysis output, which is usually done when the output is meant for another
program.

While -analyze is not given, opt attempts to produce an
optimized output file. The optimizations available via opt depend
upon what libraries were linked into it as well as any additional libraries
that have been loaded with the -load option. Use the -help
option to determine what optimizations you can use.

If filename is omitted from the command line or is “-“, opt
reads its input from standard input. Inputs can be in either the LLVM assembly
language format (.ll) or the LLVM bitcode format (.bc).

If an output filename is not specified with the -o option,
opt writes its output to the standard output.

Enable binary output on terminals. Normally, opt will refuse to
write raw bitcode output if the output stream is a terminal. With this option,
opt will write raw bitcode regardless of the output device.

opt provides the ability to run any of LLVM’s optimization or
analysis passes in any order. The -help option lists all the passes
available. The order in which the options occur on the command line are the
order in which they are executed (within pass constraints).

This option causes opt to strip debug information from the module before
applying other optimizations. It is essentially the same as -strip
but it ensures that stripping of debug information is done first.

This option causes opt to add a verify pass after every pass otherwise
specified on the command line (including -verify). This is useful
for cases where it is suspected that a pass is creating an invalid module but
it is not clear which pass is doing it.

Load the dynamic object plugin. This object should register new
optimization or analysis passes. Once loaded, the object will add new command
line options to enable various optimizations or analyses. To see the new
complete list of optimizations, use the -help and -load
options together. For example: